Field of Invention
The present invention relates to a photosensitive resin composition, a protective film formed by the photosensitive resin composition and a liquid crystal display element having the protective film. More particularly, the present invention provides a photosensitive resin composition with excellent resistance to development and leveling resistance, a protective film formed by the photosensitive resin composition and a liquid crystal display element having the protective film.
Description of Related Art
In electrical element, such as thin film transistor (TFT) liquid crystal display element, magnetic head element, integrated circuit element, solid imaging element and the like, a protective film (also called as interlayer insulating film) generally is disposed between wirings to achieve the efficacies of insulating and protective.
The materials for producing the protective film generally is selected from materials that can obtain a desired pattern by less steps and the protective film has better flatness. The materials for producing the protective film can be photosensitive resin compositions.
JP Patent publication No. 2009-075329 discloses a photosensitive resin composition for a protective film. The photosensitive resin composition for the protective film can increase adherence of the protective film by transition metal compound having structures shown as following Formula (VIII-1) or Formula (VIII-2):

in Formula (VIII-1), A represents elements of group VIA to group VIIA with an atomic valence of r, and r represents 1 or 2; R represents an aromatic group of 6 to 30 carbons, a heterocyclic group of 4 to 30 carbons, an alkyl group of 1 to 30 carbons, an alkenyl group of 2 to 30 carbons or an alkynyl group of 2 to 30 carbons; D represents a group shown as following Formula (VIII-1-1); X− represents a group shown as following Formula (VIII-1-2); and s represents an integer of 0 to 3:

in Formula (VIII-1-1) or (VIII-1-2), E represents a divalent group, such as an alkylene group of 1 to 8 carbons, an arylene group of 6 to 20 carbons, a heterocyclic compound of 8 to 20 carbons or the like; t represents an integer of 0 to 5; Rf represents an alkyl group that has at least 80% of hydrogen atoms are substituted by fluorine atoms; and u represents an integer of 1 to 5:

in Formula (VIII-2), M represents transition metal elements of group VIB to group VIII; L1 and L2 are ligands of the transition metals, L1 represents an aromatic compound of 6 to 24 carbons or a heterocyclic group of 4 to 20 carbons, and L2 represents anions of indene, fluorene or cyclopiperylene; the X− has the same definition as aforementioned definition in Formula (VII-1), rather than focusing or mentioning it in detail; w and y represents an integer of 0 to 2, and the sum of (w+y) is 2; and z represents 1 or 2.
Moreover, JP Patent publication No. 2009-229892 disclosed a photosensitive resin composition for a protective film. The photosensitive resin composition includes silesquioxane having an aromatic group of 6 to 15 carbons. The silesquioxane having an aromatic group can increase sensitivity, transmission rate and adherence of the protective film.
However, although the aforementioned two photosensitive resin compositions can enhance the adherence of the protective film, the protective film had defects of poor resistance to development and poor leveling resistance, thus lowering accuracy of the desired patterns, and further reducing the performance of the aforementioned electrical elements.
Accordingly, there is a need to provide photosensitive resin composition for a protective film with excellent resistance to development and leveling resistance for improving the disadvantages of the aforementioned defects of the conventional protective film.